Numerical modeling of time-dependent deformations of concrete at 3D analysis of structures : doctoral thesis

Beton je materijal čije je ponašanje izrazito nelinearno. Usporedno s tim, u betonu se javlja i niz sekundarnih efekata, kao što su starenje, skupljanje i puzanje betona, koji dodatno otežavaju realnu simulaciju armiranobetonskih i prenapetih konstrukcija. U moderno vrijeme, zbog sve smjelije gradnje, sve većih raspona i stremljenja u vis, potreba za realnom simulacijom ponašanja betonskih konstrukcija u uvjetima raznih vrsta opterećenja, postaje sve izraženija. S druge strane javlja se potreba za modelima koji s malim brojem realno uvjetovanih parametara mogu što vjernije opisati stvarno ponašanje betona. Jedan takav model uzet je kao osnova za ovaj rad, a to je prethodno razvijeni model, Precon 3D, koji se zasniva na malom broju parametara a dokazano može vrlo dobro opisati ponašanje betonskih, armiranobetonskih i prednapetih konstrukcija za kratkotrajna statička opterećenja. Kroz ovaj rad numerički model Precon 3D je nadograđen modelom za praćenje ponašanja betona tijekom vremena, tj. model je nadograđen modelom puzanja i skupljanja betona, što je neophodno za praćenje ponašanja prednapetih konstrukcija. Razvijeni software je testiran na više eksperimentalnih primjera iz literature, pri čemu je uočeno vrlo dobro podudaranje numeričkih i eksperimentalnih rezultata.Concrete is a material with highly nonlinear behavior. In parallel, there are numerous secondary effects in concrete, such as aging, shrinkage, and creep, which further complicate the realistic simulation of reinforced concrete and prestressed concrete structures. In modern times, due to bolder construction, increasing spans and high rising construction, the need for realistic simulation of the behavior of concrete structures under conditions of various types of loads is becoming more pronounced. On the other hand, models with a small number of real-life parameters that can describe the actual behavior of concrete as accurately as possible are necessary. One such model, the previously developed model Precon 3D, which is based on a small number of parameters and can very well describe the behavior of concrete, reinforced concrete and prestressed structures for short-term static loads was taken as the basis for this work. Through this work, the numerical model Precon 3D has been upgraded with a model for following the behavior of concrete during time, i.e. the model has been upgraded with a model of creep and shrinkage of concrete, which is necessary for following the behavior of prestressed structures. The developed software has been tested against several experimental examples from the literature, with a very good match between numerical and experimental results